Process and apparatus for the inductive surface hardening of cylindrical workpieces



April 2, 1957 G. SEULEN ETAL 2,737,566

PROCESS AND APPARATUS FOR THE INDUCTIVE SURFACE HARDENING 0F CYLINDRICAL WORKPIECES 3 Sheets-Sheet l Filed Oct Aprll 2, 1957 v G. SEULEN ETAL 2,787,566

PROCESS AND APPARATUS FOR THE INDUCTIVE SURFACE HARDENING 0F CYLINDRICAL WORKPIECEZS Flled on 15 1952 y 3 Sheets-Sheet 2 April 2, 1957 G. SEULEN ETAL 2,787,566

PROCESS AND APPARATUS FOR THE INDUCTIVE SURFACE HARDENING 0F CYLINDRICAL WORKPIECES 3 Sheets-Sheet 3 Filed Oct. 13. 1952 I I vemars;

PRGCESS AND APPARATUS FOR THEINDUCTIVE SURFACE HARDENING F CYLINDRICAL WORKPIECES Gerhard Seulen, Remscheid, Hermann Kuhlbars, Wuppertal-Elberfeld, Hermann 'Detzel, Wasseraltingen, and Adolf Wiedmann, Onatsfeld, Kreis: Aalen, Germany, assignors to Deutsche .Edelstahlwerke Akticngesellschaft, Krefeld, Germany Application October 13, 1952, Serial No. 314,474

Claims priority, application Germany October 17, 1951 11 Claims. (Cl. 148-105) The invention relates to a process of and apparatus for. the inductive surface hardening of cylindrical workpieces such as crank pin or line bearing portions of crankshafts. Hitherto it has been proposed to adopt the procedure of holding the workpiece in position with the region to be hardened opposite an electro-inductive heating station and heating it either while it is stationary or while it is in rotation and thereafter quenching it. The quenching liquid is sprayed on to the surface after the heating has been completed, either from the inductor winding or from a suitable quenching medium chamber arranged in the immediate neighborhood of the inductor.

Such procedure is however open to the objection that the shaft, especially the crankshaft, must be changed over, and the quenching times, which are substantially longer than the heating times, and the hardening station are fixed during this period, so that it cannot carry out further heating until the quenching of the heated bearing point is ended, and it is possible to employ substantially only water as quenching medium.

The process according to the invention is intended, in contrast thereto, to shorten the clamping times, to enable heating to be effected on a part or parts during the time quenching is taking place on a previously heated part or parts and to permit the quenching medium to be chosen in accordance with the properties of the material, i. e., enabling, for example, salt solutions, oil or emulsions to be employed. Salt solutions cannot be employed if sprayed from the windings, because the apertures become caked with salt and paitial short-circuiting is unavoidable. Oils cannot be used as quenching media because the oil sprayed on to the heated surface would ignite.

These disadvantages of the known processes are avoided or mitigated if, in accordance with the invention, a series of like zones on a number of workpieces, e. g., crank pins or line bearing portions of crankshafts are inductively heated in succession, and the entire workpiece is lowered into a quenching bath after each heating operation in order to make way for the next workpiece at the heating station. When end line bearing portions, for example, have thus been heated and quenched, the induction heating head is moved axially in relation to the workpieces whilst these remain held, and again in succession crank pin portions are heated and the entire workpiece lowered into the quenching medium bath forhardening after each heating operation. In this way, all the line bearing portions and crank pins (throw bearings) .are successively treated with, for example, four crankshafts simultaneously held and without longer idle periods of theinductor occurring than is necessary for moving the inductor to the new workpiece zone to be treated and axially shifting it. The hardening thus fits into a complete continuous manufacturing process in a particularly convenient manner.

When operating in this manner the quenching medium bathmay be chosen .-as desired according to 'therequirements of the material to be hardened. It may be water,

" hire States Patent 0 it: 23875 Patented Apr. 2,1957

but will preferably contain an addition for influencing the hardening properties. It is furthermore possible to employ oil, because the heated surface of the workpiece in question is immediately deeply immersed below the surface of the oil in the bath. Moreover emulsions may be used and this is particularly important in relation to alloyed materials of higher carbon content. As a precautionary measure the quenching bath may comprise different layers of liquid, the uppermost of which is noninfiamrnable to prevent ignition of the quenching bath.

As stated, the process can be applied to particular advantage to the surface hardening of the bearing zones of crankshafts. However, it may be applied to cylindrical articles of different form, for example plain shafts, shafts having sections of different diameter, camshafts or the like.

The invention further comprises an apparatus for carrying-out the process, said apparatus comprising a rotatable horizontal shaft arranged in or above a container for a quenching medium bath; a face plate mounted on this shaft and carrying a plurality of driven work-rotating heads; and the shaft having slots or grooves (or guides) along which a number of work-supporting poppet heads corresponding to the number of work-rotating heads are adapted to be secured so as to be displaceable axially of the shaft. The poppet heads may be replaced by an axially displaceable face plate comprising freely rotatable, non-driven work-supporting heads.

The apparatus according to the invention will be hereinafter more fully described with reference to a constructional example. In the example chosen, four workpieces may be simultaneously held in position, but the same general arrangement may be designed for a larger or smaller number of work-pieces. Furthermore the apparatus may be designed (if necessary with minor modifications) to treat not only single or multiple throw crankshafts, but also plain shafts, camshafts, and the like.

Figure 1 is a longitudinal section along the line A--A of figure 2.

Figure 2 is a section along the line B-B of Figure 1.

Figure 3 is a section corresponding substantially to Figure 2, showing, the electrical part, and,

Figure 4, is an elevation corresponding to Figure 3.

The carrier shaft 2 is mounted longitudinally in the upper part of the quenching medium container 1. Mounted on the said carrier shaft is a face plate 3 and connected thereto is a sleeve 4 having grooves 5 where by work-supporting poppet heads 6 are so secured to the sleeve as to be displaceable axially thereof. The workrotating members '7, driven through a planetary gear, are mounted on-the face plate '3.

The drive is effected by the motor 8 through the shaft 9 (by way of a Worm, or pinion, thereon not shown) and the worm wheel 10. In the example chosen, the speed may be varied through a t -belt drive by interchanging the belt pulleys. The speeds are transmitted through the shaft 9 to the worm wheel 16, which drives the car,- rier shaft 2 and the planet gear.

When the face plate is held fast by a locking device 11, the members -7 rotate with the shafts to be hardened held in position and the brake disc 12, while the sleeve 4 remains stationary with the face plate 3 and the poppet heads 6.

When the locking device 11 is released by the foot actuated member 13, the brake band 14 holds the brake dis-c v12 fast and the face plate 3 rot-ates together with the sleeve 4 and the poppet heads 6 through a predetermined distance, so that another shaft is brought into position for hardening. The foot actuated member maybe re placed by a hand actuated member, or the actuation may take place under'the action of a relay.

The heat treatment is efiected by induction heating,

For this purpose, for example, the crank pin 16 or linebearing portion is surrounded by a pocket-like inductor 15, the turns 17 of which form, for example, a heating conductor'loop. The said inductor 14 is secured mechanically to a linkage parallelogram 19 (pantograph) by a suitable securing means lti, and there are flexible electrical and water cooling connections to the inductor. The said pantograph enables the inductor to follow completely the movement of, for example, the crank pin of a crankshaft.

The inductor is electrically connected to the transformer -21 by flexible cables 20 and is connected to the cooling water distributor 23 for the purpose of the water supply by means of flexible pipes 22.

The inductor and the pantograph in the constructional example chosen are secured to a carriage 24 which can be moved by means of rollers 25 on the rails 26 secured to a frame on one edge of the cooling medium bath. The carriage is moved forward by means of a hand wheel 27 acting through gear wheels on the rollers of the carriage. It is thus possible to bring the inductor to any point of the shaft, for example to a line bearing portion or a crank pin. Pivoted arms for the inductor may, however, be differently constructed and if desired mounted on a bracket secured to the quenching medium receptacle. The cooling medium bath is filled with quenching liquid substantially up to the line 28. It is particularly advantageous to construct the container 1 with double walls, so that the quenching medium may be circulated by means of a pumping installation (not shown). The nozzles which return the quenching medium to the bath are preferably so arranged that their outlet apertures are substantially at the level of the various heated zones of the work so that the sections to be quenched receive sufficient cooling liquid. Furthermore, it is thus ensured that the entire quenching medium remains in constant movement.

Modifications to the apparatus are possible without departing from the underlying idea of the invention. For example, the poppet heads 6 may be replaced by a face plate on which are mounted a corresponding number of work-supporting heads adapted to rotate with reference to the face plate but not driven themselves. It is furthermore possible to employ, for example, hingeable coils as inductors, or to use inductors comprising heating conductor parts of sinuous form. Linear inductors may also be employed at suitably high frequency.

The manner of operation of the apparatus is such that after the four shafts have been held in position, the driving device is started. All the crankshafts rotate, three of them being in water. The inductor is laid on the crankshaft portion to be heated, for example on the crankrpin and follows the rotational movements thereof as described. At the same time, a medium-frequency generator is switched on. The power, heating time and compensation required are pre-set or pre-selected on the operating panel. For this purpose, the adjusting devices necessary for say five different bearing dimensions in all are provided on the panel. The associated push buttons for starting are appropriately situated on the machine. After the predetermined heating period for example 6 seconds, the installation is switched off. At the same time, the inductor device is lifted by means of the electrohydraulic lifting device 29 from the crankshaftportion that has been heated. The face plates or the face plate and poppet heads turn through 90. The heated workpiece is thus immersed in the water and quenched. The crankshafts continue themselves to rotate, whereby a good quenching effect is obtained and a thorough whirling of the water is effected. The heating device is thereafter applied to the crank pin of the next shaft and the process hereinbefore described is repeated, until all the crank pins of the four shafts are hardened. The remaining shaft portions are similarly hardened. However, the heating head must be exchanged for each different pin dimension, of which there are generally four and sometimes live, but

this can be done without any great loss of time owing to the facility with which the clamping means can be operated.

As the quenching of an already heated portion or portions is taking place whilst another portion is being heated there is a considerable saving in overall operating time. The shafts are eventually successively removed and four new shafts for hardening are introduced.

It will readily be seen that if oil is employed as quenching medium the danger of ignition is not great. However, it may if necessary be further reduced or entirely avoided by pouring on to the surface 28 a non-inflammable liquid of lower specific gravity, through which the heated workpieces can be brought beneath the surface of the bath.

Since the cooling medium nozzles which return the circulated liquid to the bath are directed towards the bearing zone of the shaft, a sufficient quenching effect is ensured with continuous rotation of the bearing points in question.

The apparatus not only affords the advantage that four shafts can be held in position in one setting-up operation, but also affords the possibility of doing this without holding the crank shafts in an eccentric position. The continuous rotation of the workpieces both during heating and during quenching prevents warping which might otherwise occur as a result of the heating.

What we claim is:

l. A process for successively bringing pin and shaftjournal portions of each of a plurality of cranksha-fts into and out of heating relation with an inductor and into and out of a quenching bath for the surface hardening thereof, which comprises bringing one of said portions of each of said crankshafts in succession to the inductor while said crankshafts are mounted in predetermined relation to one another as a unit; and subsequent to each heating operation, displacing the unit and thereby lowering the entire workpiece just heated into a quenching bath and bringing the next crankshaft simultaneously to the inductor; and after those portions of the crankshafts have been treated, redisposing the inductor and successively heating and quenching in the same manner a further said zone of each crankshaft, and during the heating of portions of a shaft rotating the shaft about its own axis and while a crankpin portion is being heated by the inductor,

. displacing the inductor in an orbital path to follow the orbit of the said pin.

2. A process for bringing the pin and shaft-journal portions of each of a plurality of crankshafts into and out of heating relation with an inductor and into and out of a quenching bath for the surface hardening thereof which comprises mounting a plurality of said crankshafts in predetermined relation to one another as a unit on a rotatable carrier so that certain of said crankshafts are immersed in the quenching bath and at least one is outside the bath with one of said portions thereof in heating relation with an inductor; continuously rotating the crankshafts about their own axes; and following the heating of said latter portion, turning the carrier to lower the corresponding crankshaft into the bath and to bring one of said portions of another crankshaft to heating position and repeating the sequence until the selected portion of each crankshaft has been treated; and thereafter relatively displacing the inductor and the carrier axially of the latter and repeating the same sequence of operations on a further portion of each crankshaft and continuing in the same manner until each portion of the crankshaft to be treated has been brought to the inductor and heated and then turned into the bath, and during the heating of a crank-pin portion, displacing the inductor in an orbital path to maintain it in eficctive heating relation to the crank-pin portion in its orbit.

3, A process according to claim 2 wherein first a given portion of one shaft is treated and then the correspondingly axially-located portion of each of the other of the plurality of crankshafts is treated before the inductor is moved to perform the same series of operations on a further portion of each shaft axially displaced with reference to the last treated portion.

4. In an apparatus for hardening crankshafts and comprising a bath for containing a quenching medium into which the crankshafts can be lowered, the combination of means comprising a carrier and means rotatably supporting it; an electric heating inductor and means supporting it; said carrier having means for detachably supporting in predetermined relationship a plurality of crankshafts for rotation about their own axes; means for so rotating said crankshafts and means for intermittently turning said carrier; and means pivotally connecting said inductor to its said supporting means so that the inductor can cooperate with a shaft-journal portion of the crankshaft or with a crank pin portion and follow the movement of said latter portion while this is revolving in an orbit resulting from the crankshaft rotation; said supporting means for the in ductor and therewith the means pivotally connecting the inductor thereto being displaceable in the direction of the axis of the said carrier so that the inductor can be moved into heating relation with the successive portions of the crankshafts to be treated.

5. In an apparatus for hardening crankshafts and comprising a bath for containing a quenching medium into which the crankshafts can be lowered, the combination of means comprising a carrier and means rotatably supporting it; an electric heating inductor and means supporting it; said carrier having means for detachably supporting in predetermined relationship a plurality of crankshafts for rotation about their own axes; means for so rotating said crankshafts and means for intermittently turning said carrier; and means pivotally connecting said inductor to its said supporting means comprising pivoted arms which are adapted to be upwardly hinged and displaced in the longitudinal direction of the carrier so that the inductor can be moved with respect to said work, and move in an orbital path following the orbital movement of a crank-pin portion.

6. Apparatus according to claim 4, the inductor heater being in the form of at least one heating conductor loop and an intermediate transformer.

7. Apparatus according to claim 4, wherein said means pivotally connecting the inductor to its supporting means includes a parallelogram linkage means.

8. Apparatus according to claim 4, including an electrically operated device for lifting the inductor from the workpiece.

9. Apparatus according to claim 8 including means whereby said electrically operated device is responsive to act after a predetermined adjustable time.

10. Apparatus according to claim 4 including an electrically operated device responsive to act to interrupt the heating at predetermined times.

11. A process for the inductive surface hardening of pin and shaft journal portions of crankshafts which comprises maintaining the crankshafts in rotation about their own axes of rotation, inductively heating one of said pin and shaft portions of each of a plurality of crankshafts in succession while the crankshafts are mounted in predetermined relation to one another as a unit and causing the inductor when heating a crank-pin portion to follow the movement of the said portion While it revolves in an orbit as a result of the crankshaft rotation, and subsequent to each heating operation, displacing the aforesaid unit and thereby lowering the entire crankshaft last locally heated into a quenching bath and bringing the next crankshaft simultaneously to the heating region and after those corresponding portions of the c-rankshafts have been hardened, redisposing the inductor and successively heating and quenching in the same manner other of said portions of each crankshaft.

References Cited in the file of this patent UNITED STATES PATENTS 1,987,752 Salzman Jan. 15, 1935 2,124,459 Burgess July 19, 1938 2,170,876 Shorter Aug. 29, 1939 2,242,158 Wasso-n May 13, 1941 2,255,103 Denneen Sept. 9, 1941 2,326,206 Dunn Aug. 10, 1943 2,349,813 Denneen May 30, 1944 2,368,809 Denneen Feb. 6, 1945 2,506,425 Jouvneaux May 2, 1950 2,634,121 Peters Apr. 7, 1953 2,665,126 Roehm Ian. 5, 1954 FOREIGN PATENTS 577,044 Great Britain May 2, 1946 

4. IN AN APPARATUS FOR HARDENING CRANKSHAFTS AND COMPRISING A BATH FOR CONTAINING A QUENCHING MEDIUM INTO WHICH THE CRANKSHAFTS CAN BE LOWERED, THE COMBINATION OF MEANS COMPRISING A CARRIER AND MEANS ROTATABLY SUPPORTING IT; AN ELECTRIC HEATING INDUCTOR AND MEANS SUPPORTING IT; SAID CARRIER HAVING MEANS FOR DETACHABLY SUPPORTING IN PREDETERMINED RELATIONSHIP A PLURALITY OF CRANKSHAFTS FOR ROTATION ABOUT THEIR OWN AXES; MEANS FOR SO ROTATING SAID CRANKSHAFTS AND MEANS FOR INTERMITTENTLY TURNING SAID CARRIER; AND MEANS PIVOTALLY CONNECTING SAID INDUCTOR TO ITS SAID SUPPORTING MEANS SO THAT THE INDUCTOR CAN CO-OPERATE WITH A SHAFT-JOURNAL PROTION OF THE CRANKSHAFT OR WITH A CRANK PIN PROTION AND FOLLOW THE MOVEMENT OF SAID LATTER PROTION WHILE THIS IS REVOLVING IN AN ORBIT RESULTING FROM THE CRANKSHAFT ROTATION; SAID SUPPORTING MEANS FOR THE INDUCTOR AND THEREWITH THE MEANS PIVOTALLY CONNECTING THE INDUCTOR THERETO BEING DISPLACEABLE IN THE DIRECTION OF THE AXIS OF THE SAID CARRIER SO THAT THE INDUCTOR CAN BE MOVED INTO HEATING RELATION WITH THE SUCCESSIVE PORTIONS OF THE CRANKSHAFTS TO BE TREATED. 